Theoretical Study for Adsorption–Diffusion on H-MOR and Pyridine Pre-adsorbed H-MOR of Dimethyl Ether Carbonylation

Abstract

For dimethyl ether (DME) carbonylation, pyridine pre-adsorbed hydrogen mordenite (H-MOR) is beneficial to prolonging the catalyst life. The adsorption and diffusion behaviors on periodic models H-AlMOR and H-AlMOR-Py were simulated. The simulation was based on Monte Carlo and molecular dynamics. The following conclusions were drawn from the simulation results. The adsorption stability of CO in 8-MR is increased, and the adsorption density of CO in 8-MR is more concentrated on H-AlMOR-Py. 8-MR is the main active site for DME carbonylation, so the introduction of pyridine would be beneficial for the main reaction. The adsorption distributions of methyl acetate (MA) (in 12-MR) and H2O on H-AlMOR-Py are significantly decreased. It means the product MA and the byproduct H2O are more easily desorbed on H-AlMOR-Py. For the mixed feed of DME carbonylation, the feed ratio (P CO/P DME) must reach 50:1 on H-AlMOR so that the reaction molar ratio can reach the theoretical value (N CO/N DME ≈ 1:1), while the feed ratio on H-AlMOR-Py is only up to 10:1. Thus, the feed ratio can be adjusted, and raw materials can reduce consumption. In conclusion, H-AlMOR-Py can improve the adsorption equilibrium of reactants CO and DME and increase the concentration of CO in 8-MR.

Solid-State Au Nanocone Arrays Substrate for Reliable SERS Profiling of Serum for Disease Diagnosis

“…In recent years, surface-enhanced Raman spectroscopy (SERS) has gained widespread usage for the detection and identification of molecules through amplifying the characteristic Raman spectra of surface-adsorbed molecules with high enhancement factors (up to 10 8 or more) via the excitation of localized surface plasmon resonances (LSPR) on noblemetal surfaces. 1 This technology has been deployed in numerous areas, including catalysis, 2,3 electrochemistry, 4,5 biology, 6,7 medicine, 8,9 materials science, 10,11 and other applications. Raman spectroscopy, particularly, has been used as a rapid and noninvasive detection tool for disease diagnosis in medical testing.…”